/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.dx.dex.file;

import java.util.ArrayList;
import java.util.Collection;
import java.util.TreeMap;

import com.android.dx.rop.cst.Constant;
import com.android.dx.rop.cst.CstType;
import com.android.dx.rop.type.Type;
import com.android.dx.rop.type.TypeList;
import com.android.dx.util.AnnotatedOutput;
import com.android.dx.util.Hex;

/**
 * Class definitions list section of a {@code .dex} file.
 */
public final class ClassDefsSection extends UniformItemSection {

	/**
	 * {@code non-null;} map from type constants for classes to
	 * {@link ClassDefItem} instances that define those classes
	 */
	private final TreeMap<Type, ClassDefItem> classDefs;

	/** {@code null-ok;} ordered list of classes; set in {@link #orderItems} */
	private ArrayList<ClassDefItem> orderedDefs;

	/**
	 * Constructs an instance. The file offset is initially unknown.
	 * 
	 * @param file
	 *            {@code non-null;} file that this instance is part of
	 */
	public ClassDefsSection(DexFile file) {
		super("class_defs", file, 4);

		classDefs = new TreeMap<Type, ClassDefItem>();
		orderedDefs = null;
	}

	/** {@inheritDoc} */
	@Override
	public Collection<? extends Item> items() {
		if (orderedDefs != null) {
			return orderedDefs;
		}

		return classDefs.values();
	}

	/** {@inheritDoc} */
	@Override
	public IndexedItem get(Constant cst) {
		if (cst == null) {
			throw new NullPointerException("cst == null");
		}

		throwIfNotPrepared();

		Type type = ((CstType) cst).getClassType();
		IndexedItem result = classDefs.get(type);

		if (result == null) {
			throw new IllegalArgumentException("not found");
		}

		return result;
	}

	/**
	 * Writes the portion of the file header that refers to this instance.
	 * 
	 * @param out
	 *            {@code non-null;} where to write
	 */
	public void writeHeaderPart(AnnotatedOutput out) {
		throwIfNotPrepared();

		int sz = classDefs.size();
		int offset = (sz == 0) ? 0 : getFileOffset();

		if (out.annotates()) {
			out.annotate(4, "class_defs_size: " + Hex.u4(sz));
			out.annotate(4, "class_defs_off:  " + Hex.u4(offset));
		}

		out.writeInt(sz);
		out.writeInt(offset);
	}

	/**
	 * Adds an element to this instance. It is illegal to attempt to add more
	 * than one class with the same name.
	 * 
	 * @param clazz
	 *            {@code non-null;} the class def to add
	 */
	public void add(ClassDefItem clazz) {
		Type type;

		try {
			type = clazz.getThisClass().getClassType();
		} catch (NullPointerException ex) {
			// Elucidate the exception.
			throw new NullPointerException("clazz == null");
		}

		throwIfPrepared();

		if (classDefs.get(type) != null) {
			throw new IllegalArgumentException("already added: " + type);
		}

		classDefs.put(type, clazz);
	}

	/** {@inheritDoc} */
	@Override
	protected void orderItems() {
		int sz = classDefs.size();
		int idx = 0;

		orderedDefs = new ArrayList<ClassDefItem>(sz);

		/*
		 * Iterate over all the classes, recursively assigning an index to each,
		 * implicitly skipping the ones that have already been assigned by the
		 * time this (top-level) iteration reaches them.
		 */
		for (Type type : classDefs.keySet()) {
			idx = orderItems0(type, idx, sz - idx);
		}
	}

	/**
	 * Helper for {@link #orderItems}, which recursively assigns indices to
	 * classes.
	 * 
	 * @param type
	 *            {@code null-ok;} type ref to assign, if any
	 * @param idx
	 *            {@code >= 0;} the next index to assign
	 * @param maxDepth
	 *            maximum recursion depth; if negative, this will throw an
	 *            exception indicating class definition circularity
	 * @return {@code >= 0;} the next index to assign
	 */
	private int orderItems0(Type type, int idx, int maxDepth) {
		ClassDefItem c = classDefs.get(type);

		if ((c == null) || (c.hasIndex())) {
			return idx;
		}

		if (maxDepth < 0) {
			throw new RuntimeException("class circularity with " + type);
		}

		maxDepth--;

		CstType superclassCst = c.getSuperclass();
		if (superclassCst != null) {
			Type superclass = superclassCst.getClassType();
			idx = orderItems0(superclass, idx, maxDepth);
		}

		TypeList interfaces = c.getInterfaces();
		int sz = interfaces.size();
		for (int i = 0; i < sz; i++) {
			idx = orderItems0(interfaces.getType(i), idx, maxDepth);
		}

		c.setIndex(idx);
		orderedDefs.add(c);
		return idx + 1;
	}
}
